1. Field of the Invention
The present invention relates to a shielded electronic circuit unit that is suitable for a voltage controller or the like and a method of manufacturing the same.
2. Description of the Related Art
FIG. 36 is a cross-sectional view illustrating a main portion of an electronic circuit unit according to the related art, and FIG. 37 is a cross-sectional view of a main portion illustrating a method of manufacturing the electronic circuit unit according to the related art. Next, a structure of the electronic circuit unit according to the related art will be described with reference to FIG. 36. In a multi-layered substrate 51, a wiring pattern P1, which has signal patterns 52 and grounding patterns 53, is provided. The signal patterns 52 of the wiring pattern P1 are provided on a top surface and laminated layers (inner laminated layers) of the multi-layered substrate 51, and have terminal portions 52a that are provided on lower portions of the side surfaces of the multi-layered substrate 51. In addition, the grounding patterns 53 are provided on the top surface and the bottom surface of the multi-layered substrate 51.
Each of electronic components 54, which are made of chip components, has first and second electrodes 54a and 54b provided on both ends. The electronic component 54 is disposed on a top surface of the multi-layered substrate 51. In the electronic component 54, the first electrode 54a is soldered to the signal pattern 52, and the second electrode 54b is soldered to the grounding pattern 53. Therefore, the electronic component 54 is mounted on the top surface of the multi-layered substrate 51.
A sealing resin portion 55 is made of an insulating material. In a state in which the sealing resin portion 55 buries the electronic components 54, it is provided on the top surface of the multi-layered substrate 51. In the sealing resin portion 55, a blind hole 55a is provided so as to extend from the top surface of the sealing resin portion 55 to the second electrode 54b for grounding.
In addition, a metallic film 56, which performs an electrical shield function, is provided on the top surface of the sealing resin portion 55, the wall surface of the blind hole 55a, and the second electrode 54b located at the bottom portion of the blind hole 55a. In this way, the electronic circuit unit according to the related art is formed.
In the electronic circuit unit according to the related art having the above-mentioned structure, although not shown, the bottom surface of the multi-layered substrate 51 is disposed on a mother substrate. In addition, the terminal portions 52a, which are provided on the side surface of the multi-layered substrate 51, are soldered to a conductive pattern provided on the mother substrate. As a result, the electronic circuit unit according to the related art is surface-mounted on the mother substrate.
However, the electronic circuit unit according to the related art has a structure in which the metallic film 56 performing an electrical shield function is provided on the only the top surface of the sealing resin portion 55. As a result, an electrical shield effect through the metallic film 56 is insufficient. In addition, since the metallic film 56 is provided in the blind hole 55a, in particular, when the metallic film 56 is formed by means of a plating method, the circulation of a plating liquid is insufficient in the blind hole 55a. As a result, the metallic film 56 is unstably attached to the second electrode 54b. 
Then, a method of manufacturing the electronic circuit unit according to the related art will be described with reference to FIG. 37. First, an assembly substrate 57 is prepared so as to form the plurality of multi-layered substrates 51, and electronic components 54 are mounted so as to correspond to a plurality of multi-layered substrates 51 in the assembly substrate 57.
Then, the electronic components 54 are buried in the top surface of the assembly substrate 57, and the sealing resin portion 55 having the blind hole 55a provided at a location of the second electrode 54b are provided. Then, a metallic film 56 is provided which is formed on the top surface of the sealing resin portion 55 and in the blind hole 55a, and connected to the second electrode 54b. Then, at the location between the adjacent multi-layered substrates 51, the assembly substrate 57 and the sealing resin portion 55 are cut at a location of a cutting line S3 such that electronic circuit units are individually separated from each other. In this way, the electronic circuit unit according to the related art is completely manufactured.
However, in the method of manufacturing the electronic circuit unit according to the related art, the metallic film 56 for performing the electrical shield function is provided on only the top surface of the sealing resin portion 55. As a result, the electrical shield effect through the metallic film 56 is insufficient. In addition, since the metallic film 56 is provided in the blind hole 55a, in particular, when the metallic film 56 is formed by means of a plating method, the circulation of a plating liquid is insufficient in the blind hole 55a. As a result, the metallic film 56 is unstably attached to the second electrode 54b. 
According to the electronic circuit unit and the method of manufacturing the same according to the related art, the electronic circuit unit according to the related art has a structure in which the metallic film 56 for performing an electrical shield function is provided on the only the top surface of the sealing resin portion 55. As a result, the electrical shield effect through the metallic film 56 is insufficient. In addition, since the metallic film 56 is provided in the blind hole 55a, in particular, when the metallic film 56 is formed by means of a plating method, the circulation of a plating liquid is insufficient in the blind hole 55a. As a result, the metallic film 56 is unstably attached to the second electrode 54b. 